"If David Hume had designed the Cybermen to be perfectly reasonable but emotionless, they'd do nothing at all. They'd have no impetus since they'd care about nothing. Mondas would simply drift past the Earth in "The Tenth Planet." Human scientists would no doubt eagerly attempt to contact this newly discovered form of alien life, but the Cybermen wouldn't even wave back at our telescopes. When the new Cybermen are brought to John Lumic, he'd bark orders at them only to be ignored by creatures who, lacking emotions, care no more about what he wants than about whether they live or die. Cybermen built to be reasonable but lacking emotion would be a race indistinguishable from statues, fit only to serve as shop mannequins."